This invention pertains to carts with lockable drawers and more particularly to a keyless locking system for medical carts.
Carts with lockable drawers are used for many applications. For example, a medical cart is used to administer medication to patients in hospitals or other care facilities. A typical medical cart has casters located at the bottom of the cart to permit easy movement of the cart by attending nurses to various patients"" rooms. The cart also has one or more drawers for storing patients"" medicines. Typically, each drawer is dedicated to storing the medication for an individual patient. Because the cart is used to store medications for several patients and is moveable from room to room, controlling access to the contents of the cart to prevent theft or misuse of medication and thereby protect the patients is important. One such medical cart, as described above, is disclosed in U.S. Pat. No. 5,743,607, to Teufel et al., which patent is commonly held by the assignee of the present invention and hereby incorporated by reference in its entirety.
Controlling access to medical carts in the past involved the use of manual key locks or complex electromechanical devices which permit a drawer locking tab to lock and unlock all of the drawers of the medical cart. U.S. Pat. No. 5,743,607, for example, discloses the use of a keypad with a system of locking tabs to lock the drawers of a cart. These prior art methods of locking carts or controlling access to medical carts, while being effective, do have certain limitations. For example, the keys for a manually locked cart can be lost or misappropriated by unauthorized persons. In the event that a key is lost and controlled access to the cart has been compromised, the changing of a keyed lock requires considerable time and expense during which time the cart cannot be used. In the case of electromechanical locks, prior art locking systems generally consume a considerable amount of power, requiring the systems to be charged daily for proper operation of the electromechanical locking mechanism. Furthermore, service, maintenance, and manufacture of prior art carts may be generally expensive and time consuming due to the complexity of the locking mechanisms.
Accordingly, there is a need for a simple, keyless cart locking system having low power consumption requirements and which is easy to manufacture and maintain, particularly for medical carts having lockable drawers.
This invention, in one embodiment, is a locking system for a cart with lockable drawers, such as a medical cart, and in another embodiment the invention is a cart with such a locking system. The locking system includes an integrated circuit which controls the actuation of a drive mechanism in the form of a solenoid to permit the operation by a user of a handle for release of the drawers. Advantageously, power to the solenoid is only provided to disengage the lock mechanism when a correct access code has been entered via a keypad or other user input device. Previously, locking mechanisms for carts of this type required a significant amount of power for actuation of the drive and lock mechanisms. Since this invention only briefly consumes power to disengage the drive mechanism, the system has very low power consumption requirements. The simple design of the locking mechanism also makes it easy to operate, manufacture and service.
The invention includes a lock mechanism having a handle which is manipulated by a user to disengage a locking tab of the medical cart. The lock mechanism includes a housing which supports the handle and a spring-loaded cam to disengage the locking tab. The lock mechanism further includes a drive mechanism in the form of a solenoid having a movable armature that positively engages the handle portion of the lock mechanism to prevent the lock mechanism from disengaging the locking tab when the solenoid is in an unenergized, or xe2x80x9cno loadxe2x80x9d state. The solenoid is connected to an integrated circuit having a keypad to accept user input such as an access code, and also to a power supply which provides power to the solenoid when the correct access code has been entered into the keypad. In a preferred embodiment, the power supply includes four D cell batteries to energize the solenoid on demand when the cart is to be unlocked.
The locking system of this invention preferably includes a manual override device to gain access to the drawers of the cart in the event of a loss of power or in the event the access code has been lost. The manual override device includes a flexible yoke which is connected to the armature of the solenoid. The yoke is actuated to disengage the armature from the handle by a conventional key lock coupled to and remotely located from the lock mechanism. In a preferred embodiment, the yoke is coupled to the remote key lock by a cable.
In another aspect of the invention, the housing of the lock mechanism has a clam-shell design, with hinges that facilitate easy assembly. The lock mechanism also includes a rod and handle assembly for an operator to disengage the drawer locking tabs of the cart. In this regard, the rod has a cam at one end which protrudes from the housing to move the locking tabs from a locked configuration to an unlocked configuration. The handle is inserted into an end of the housing opposite from the cam and is coupled to the rod.